look at uptaking some of the performance and fast-fail BigDecimal parser code from jsoniter-scala

[pjfanning]

Maybe something for jackson v2.15. Idea is to enhance the existing BigDecimalParser class.

@plokhotnyuk suggested looking at https://github.com/plokhotnyuk/jsoniter-scala/blob/3b062f77f566d64b68b765ceed3738ad93d475dc/jsoniter-scala-core/native/src/main/scala/com/github/plokhotnyuk/jsoniter_scala/core/JsonReader.scala#L1647-L1874

He provides some analysis at https://stackoverflow.com/a/58777171/228843

He provided some benchmarks at FasterXML/jackson-module-scala#572 (comment)

[pjfanning]

I have a prototype at https://github.com/pjfanning/jackson-number-parse-bench/blob/main/src/main/java/org/example/jackson/bench/FastBigDecimalParser.java

• it is a little faster than the existing parser
• it still needs more testing and some more error handling. It may be possible to get a little bit better perf from it.
• it still works by taking a full String or char[] with the number as opposed to working directly on the input data stream like the jsoniter-scala does - so it won't match jsoniter-scala performance.

[cowtowncoder]

I think it's fine to require copy as char[] or String; although I guess some parser backends could conceivably pass offsets to internal char[] quite easily. But it does not seem like a humongous overhead regardless; at most it's good to maybe avoid throw-away String instances (which I think is doable).

[pjfanning]

The current benchmark for FastBigDecimalParser suggests it is better for numbers with lots of digits (and still a little better for numbers with a small number of digits).

For BigInteger parsing, I got:

Benchmark                                 Mode  Cnt       Score       Error  Units
BigIntegerParserBench.bigDec1000         thrpt    5   35195.566 ±  2758.478  ops/s
BigIntegerParserBench.bigDec10000        thrpt    5    1232.178 ±   221.485  ops/s
BigIntegerParserBench.bigDec1000000      thrpt    5       0.396 ±     0.031  ops/s
BigIntegerParserBench.bigInt1000         thrpt    5   48308.680 ±   671.193  ops/s
BigIntegerParserBench.bigInt10000        thrpt    5     617.721 ±    14.032  ops/s
BigIntegerParserBench.bigInt1000000      thrpt    5       0.063 ±     0.002  ops/s
BigIntegerParserBench.fastBigDec1000     thrpt    5  138409.766 ± 10781.948  ops/s
BigIntegerParserBench.fastBigDec1000000  thrpt    5       2.342 ±     0.019  ops/s

[pjfanning]

I'll close this as we have gone down the route of using https://github.com/wrandelshofer/FastDoubleParser

jsoniter-scala is actually faster but it parses the number as it streams the bytes/chars instead of building up strings and parsing those as numbers like Jackson does. Changing Jackson do this would be quite some refactor.

[cowtowncoder]

Agreed, FDP seems to work for now.